In a postal sorting machine, and more particularly in a type “TOP 2000” machine manufactured by the supplier “Solystic”, mail items traveling on an inlet conveyor are injected into a sorting conveyor by means of an intermediate injection carousel. This operation of transferring mail items is particularly critical for the performance of the sorting machine. It determines the speed at which mail items are processed by the sorting machine, so the items must be transferred in minimum time and at an injection rate into the carousel of about six items per second.
The mail items processed by that machine are mainly flat objects of all kinds that can be rigid, flexible, plasticized, made of paper, of width lying in the range 90 millimeters (mm) to 300 mm, of length lying in the range 140 mm to 400 mm, and of thickness lying in the range 0.2 mm to 32 mm.
A postal sorting machine of the kind described above is disclosed in patent document FR-2 795 396. In that prior device, mail items are conveyed standing on edge between two rows of wheels constituting the injection system, and at the outlet they are sent from the rows of wheels into receptacles of the carousel. That injection system enables the speed at which mail items are injected into the receptacles to be adjusted. The mail items are moved standing on edge in the receptacles of the carousel, prior to falling vertically, under gravity, edge-on into slots of a sorting conveyor synchronized with the carousel.
The use of such a system for injecting mail items into the receptacles of the carousel is satisfactory only for mail items that are rigid, heavy, and large in size.
Flexible mail items tend to sag between the walls of the receptacle. In addition, sending items at high speed into the receptacles of the carousel causes items that are not very rigid to become deformed under the effects of friction generated by the speed and by impacts against the walls. Finally, the stirring of the air, due to the carousel rotating and to air being compressed by variation in the spacing between the walls of the receptacles as the carousel rotates, leads to disturbances of the ambient air in the item injection zone, thereby changing the trajectories of certain lightweight mail items.
The deformation of mail items and the changes to their trajectories on being injected into the receptacles of the carousel are the main causes of machines being stopped and of mail items being rejected from the sorting conveyor, thereby slowing down operation of the sorting machine and requiring operators to intervene.
A mail item that is poorly injected into a receptacle of the carousel, i.e. that is not standing on its edge at the end of the receptacle corresponding to its entry position, does not drop vertically straight into the corresponding slot of the sorting conveyor, but spreads out flat, e.g. over the surfaces of a plurality of slots, or falls into another slot together with another mail item. Mail items that are badly inserted into the slots of the sorting conveyor are detected and rejected, or else they are removed using an ejection brush, when the articles lie over a plurality of slots.
Those injection problems lead to a high ratio of mail items being absent from the slots of the sorting conveyor, which items need to be processed manually.
The device for injecting mail items from the inlet conveyor to the intermediate carousel as described above does not come up to the expectations by users of postal sorting machines, since up to 2% of mail items are injected badly.
The object of the invention is to remedy the drawbacks described above by proposing a postal sorting machine in which improved means are provided for bringing mail items in a straight vertical position at the ends of the receptacles of the carousel and for maintaining them in that position.